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Here we report new concept of neutron detector with Microstructure Boron Layer. Our new Microstructure Boron Layer is developed to improve the neutron detection efficiency of boron film converter. Microstructure is constructed on aluminum substrate and enriched boron 10 is deposited for 2 to 4 µm thick. The Microstructure were combined with GlassGEM and tested in reclectometry beam line of J-PARC...
Epitaxial growth of intermetallic compounds formed at eutectic Sn37Pb/ polycrystalline Cu interface during solid-state aging. The results show that the interfacial Cu6Sn5 grains exhibit textured growth under solid-state condition and their preferred orientations are affected by the as-soldered joints. Cu6Sn5 grains with [0001] direction normal to the interface are stable in solid and molten Sn37Pb...
Co-electrodeposition is an economic and effective method to prepare Au-Sn solder bumps. Au-Sn solder bumps were prepared in a non-cyanide sulfite-pyrophosphate Au-Sn electroplating bath in the present work. The content of Sn in the deposited Au-Sn solder bumps was precisely controlled to be 30 at.%, i.e., Au-Sn eutectic composition. The interfacial reactions of the co-electrodeposited eutectic Au-30at...
Lead-free solder joints in electronic packages experience the thermal cycles as the electronic packaging products encounter the temperature fluctuations. This study provides some prospectives into the microstructural changes of the solder joints interconnection by rapid thermal cycles. The goal of this paper is to investigate the thermal fatigue behavior of a single Sn-3.0Ag-0.5Cu (SAC) lead-free...
The interfacial microstructure and Kirkendall voids between eutectic SnIn and polycrystalline Cu substrate was investigated after reflowing and long-term solid-state aging process. The results indicated that two crystal-structure IMC species: Cu(In, Sn)2 phase existing at the solder side and Cu2(In, Sn) phase locating at the Cu side, among which Cu2(In, Sn) phase with two different morphologies, the...
The main objective of this paper is to investigate the reliability of low-Ag lead-free solder alloy. The wettability, mechanical property and microstructure of Sn-1.0Ag-0.5Cu (SAC105) and Sn-3.0Ag-0.5Cu (SAC305) lead-free solder alloys were comparatively investigated. Experimental studies have shown that the wetting property of low-Ag lead-free solder alloy SAC105 remains to be improved and mechanical...
The growth kinetics and morphology of the interfacial intermetallic compound (IMC) Cu6Sn5 between Sn-3Ag-0.5Cu-xFe (x= 0, 0.5wt.%, 1wt.%) composite solders and Cu substrate during aging were investigated in the present work. The Sn-Ag-Cu-Fe/Cu solder joint were prepared by reflowing for various durations at 250 °C and then aged at 150 °C. The Fe element tended to suppress the growth of the Cu3Sn layer...
Joining semiconductor chips at low temperatures (below 300 °C) by sintering nanosilver paste is emerging as an alternative, lead-free solution for power electronic packaging, especially high-temperature applications, because of high melting temperature of silver (961 °C). However, silver is susceptible to migration. In this paper, we studied effects of temperature, DC bias, and electrode spacing on...
The solidification behavior and microstructure of Ni/Sn-3.0Ag-0.5Cu/Cu joint were investigated by using DSC. It was found that the degree of undercooling for Sn-3.0Ag-xCu(x≥0.5wt.%) solders increased with increasing the concentration of Cu and the addition of Ni increased the degree of undercooling of Sn-3.0Ag-0.5Cu significantly. The addition of Ni changed the volume fraction of primary solidification...
Microstructure evolutions of as-reflowed and aged electroplated Cu/Sn/Cu sandwich structure with 20 or 40μm Sn layer have been investigated. Cu3Sn was observed at lower side of Cu/Sn/Cu structure with 40μm Sn layer after isothermal aging treatment for 24 hours, as for that structure with 20μm Sn layer, Cu3Sn appeared after aging for 48 hours. Regardless of Sn volume, the thickness of the blanket Cu...
Cu/Al joints with large faying surface and high bonding ratio were fabricated with an ultrasound-assisted fluxless brazing method using a Zn-3Al near eutectic filler metal. The microstructure, tensile strength, and corrosion resistance of the joints were investigated in terms of brazing temperature. Results showed that, in the joint brazed at 440 ºC, the filler metal layer showed a refined and dispersed...
The feature size of transistors is continuously decreasing while the wafer size is increasing, which presents new challenges to the interconnection between the chips and substrates. Currently, substrate has become the most influential factor of the cost in electronic packaging. In packaging substrate, the most commonly used conducting metal is copper, which is generally fabricated by electroplating...
The wettability of the molten lead-free solder on the substrate is an important property for the lead-free solder joints in electronic products. In this paper, we investigated the wettability of lead-free solder pastes on electroplated Co-P films. We measured the contact angles of one kind of Sn-Bi and two kinds of Sn-Ag-Cu (SAC305 and SAC387) solder pastes on the Co-P films with nanocrystalline,...
The developments of SiC power devices have been dramatically advanced for the last several years, and are gaining much attention as a key technology for the low carbon society. These SiC power devices are expected to work under the high temperature condition of 250–300 °C because of the wide band-gap energy and the high heat resistance. To meet the high temperature operations, the die-bonding materials...
Pure Zn exhibits excellent properties for high temperature lead-free solder such as the high melting point (419.5°C), surpassing tensile strength, high thermal and electrical conductivity, in addition to the reasonable cost. However, the brittleness and oxidation of pure Zn can potentially cause a reliability problem, when it is employed at high operation temperature expected for SiC power devices...
In this Project, we designed and set up an experiment to measure the bonding strength. Silver (Ag) layer is used as a bonding medium between copper (Cu). The upper Cu is called Cu chip and the lower Cu is Cu substrate. Both Copper (Cu) and silver (Ag) are ductile metal with very excellent electrical and thermal conductivity. Samples with structure of Cu/Ag/Cu are manufactured using solid-state bonding...
Os-Ru thin films with varying concentrations of W were sputter deposited on Mo-Re substrates. The films were analyzed with XRD to investigate their crystal structures and a Kelvin Probe to investigate their work functions. A film with ∼30 at.% W yielded a work function maximum of approximately 5.15 eV.
New techniques for manipulating surface wettability have been recently presented [1,2] and a wide variety of techniques have been developed for fabricating 3D structures of interest in the optics, photonics and nanotechnology fields. The so called soft lithography is able to transfer microscale patterns to a substrate by using an elastomeric stamp or mold, typically made of polydimethylsiloxane (PDMS)...
We have developed a facile, versatile and low-cost fabrication method for high-performance superlyophobic surfaces (SLS, simultaneously superhydrophobic and superoeleophobic) on curable materials, which is promising to unblock the two bottlenecks of SLS (relying on very few materials and requiring demanding fabrication). By using poly(dimethylsiloxane) (PDMS) as the elastomer mold, T-shape microstructures...
In this paper, we focus on the development of membrane-typed metal mould with microstructures for imprinting. This mould has several benefits including reusable, easy replaceable core, and low cost that strongly improves industrial values in microstructure mass production. The membrane-typed metal mould with a thickness of 60 µm can be attached to a level mould or a roller mould, and becomes a metal...
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